1. Field of the Invention
The present invention relates to a plasma generation apparatus for generating toroidal plasma.
2. Description of Related Art
An electric field-coupling plasma generation apparatus and an inductive-coupling plasma generation apparatus are known as apparatuses for generating plasma for plasma processing. The electric field-coupling plasma generation apparatus adds a high-frequency electric field to a material gas in a chamber using an electrode so as to generate plasma. On the other hand, the inductive-coupling plasma generation apparatus generates a high-frequency magnetic field by allowing a high-frequency current to flow in an induction coil and generates a high-frequency electric field in a chamber using the high-frequency magnetic field, whereby the material gas in the chamber becomes plasma. The material gas subjected to plasma generation is used in plasma processing as a reactive gas.
For example, Japanese Patent No. 4070152 discloses an inductive-coupling plasma generation apparatus for generating toroidal plasma. Note that “toroidal plasma” is plasma in a toroidal shape. The plasma generation apparatus allows a high-frequency current to flow in a primary winding wrapped around a magnetic core surrounding a portion of the chamber, and thereby causes magnetic flux in the magnetic core to change, thus generating a high-frequency electric field in the chamber.
However, in the case of using the plasma generation apparatus disclosed in Japanese Patent No. 4070152, the chamber and the primary winding are arranged such that their positions are physically separate, and a secondary circuit formed by the plasma in the chamber and the primary winding have separate positions. Accordingly, the coupling force decreases due to magnetic flux leakage.